When i was her age i had also some specific fears which made my father angry because l literally won't comply with his biddings because i was so afraid of somethings.
It seems there is no rationalization for the thing that you fear. All you can really do is to fight it. The night and the darkness cast a large shadow on the things we fear which makes it all too real.
Getting angry won't do her any good, understanding her fears finally made jer lie down in her own bed. But i can still hear her sobbing. Hayyy..